> Anyone who knows anything realises banning things is a) impossible and
Maybe "It's really hard" is more accurate? We (humanity) for most part basically agreed to ban the usage of various chemical weapons in wartime, which seems to have drastically reduced the usage of it, even though it's still used by shit actors today from time to time. But it's hard to deny that usage didn't decrease after banning it, which makes "banning" maybe not completely useless for certain things.
"Banning" things that can be easily copied over cyberweb transportation pipes feels like an fool's errand though, regardless of what it is. It's just too easy to get around, compared to actual physical items I suppose.
This is different now. US labs and companies are not releasing frontier-level models openly (specially those capable of assisting cyber intelligence work), but commercializing them instead. Thus, any ban would not be symmetrical to begin with, and that is precisely what maintains the balance.